Abstract

Improvements in the manner in which the potential energy surface (PES) is generated in the vibrational self-consistent field (VSCF) method have been implemented. The PES can now be computed over a flexible range of displacements and following normal mode displacement vectors expressed in internal rather than Cartesian coordinates, leading to higher accuracy of the calculated vibrational frequencies. The coarse-grained parallelization of the PES calculations, which is computationally by far the most expensive part of the VSCF method, enables the usage of higher levels of theory and larger basis sets. The new VSCF procedure is discussed and applied to three examples, , , and , to illustrate its accuracy and applicability.

Received 20 May 2008Accepted 28 August 2008Published online 24 October 2008

Acknowledgments:

This work was supported by a grant from the Air Force Office of Scientific Research. The authors are grateful for many helpful discussions with Dr. Jerry Boatz, Dr. Ryan Olson, Dr. Michael Schmidt, and Professors Benny Gerber and Lyudmila Slipchenko. The coarse-grained parallel calculations were carried out on the Scalable Computing Laboratory IBM Power4 cluster, and on the Iowa State University BlueGene/L computer, made available via grants from the National Science Foundation (Professor S. Aluru, PI), the Iowa State University Plant Sciences Institute, and Iowa State University.